Avelina Montserrat Conejo Ruiz (born February 3, 1993) is a Mexican mixed martial artist who competes in the women's Strawweight division of the Ultimate Fighting Championship (UFC).

At the age of 16, Ruiz started practicing Olympic wrestling at the Técnica 1 in León, Guanajuato, later became a national selection, living for three years at the Centro Nacional de Alto Rendimiento (CNAR) in Mexico City and then made the leap to MMA. She was a 7-time national champion in Mexico.

Montserrat Ruiz made her professional MMA debut in 2014 at the Gladiators Coliseum, a promoter in Mexico. She achieved a winning streak of nine fights fighting under various MMA promotions in Mexico, including Xtreme Fighters Latino, before entering the American circuit.

Ruiz made her promotional debut for Invicta FC against UFC vet Danielle Taylor at Invicta FC 33 on December 15, 2018. She lost the fight via unanimous decision.

After the loss to Danielle, she suffered an injury that kept her out of the cage for more than a year.

In her sophomore performance, Ruiz faced Janaisa Morandin on July 30, 2020, at Invicta FC 41: Morandin vs. Ruiz. She won the bout with ease through first round scarf hold keylock submission.

Ruiz was scheduled to face Emily Ducote for the vacant Invicta FC Strawweight Championship at Invicta FC 43, however on the day of the event, the fight was cancelled due to COVID precautions.

Ruiz made her UFC debut as a short notice replacement for Kay Hansen against Cheyanne Buys on March 20, 2021, at UFC on ESPN: Brunson vs. Holland. She won the bout via unanimous decision, keeping Buys in the headlock position for most of the bout.